r:RngSig. IsField(r)   

latex

Up	rings 1
Definitions of Statement	IsField(r)
Definitions	P  Q, P & Q, IsField(r), , t  T, x:A. B(x)
Lemmas	rng sig wf, ring divs wf, rng one wf, rng zero wf, rng car wf, nequal wf